// SPDX-License-Identifier: GPL-2.0-or-later /* X.509 certificate parser * * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) */ #define pr_fmt(fmt) "X.509: "fmt #include #include #include #include #include #include #include "x509_parser.h" #include "x509.asn1.h" #include "x509_akid.asn1.h" struct x509_parse_context { struct x509_certificate *cert; /* Certificate being constructed */ unsigned long data; /* Start of data */ const void *key; /* Key data */ size_t key_size; /* Size of key data */ const void *params; /* Key parameters */ size_t params_size; /* Size of key parameters */ enum OID key_algo; /* Algorithm used by the cert's key */ enum OID last_oid; /* Last OID encountered */ enum OID sig_algo; /* Algorithm used to sign the cert */ u8 o_size; /* Size of organizationName (O) */ u8 cn_size; /* Size of commonName (CN) */ u8 email_size; /* Size of emailAddress */ u16 o_offset; /* Offset of organizationName (O) */ u16 cn_offset; /* Offset of commonName (CN) */ u16 email_offset; /* Offset of emailAddress */ unsigned raw_akid_size; const void *raw_akid; /* Raw authorityKeyId in ASN.1 */ const void *akid_raw_issuer; /* Raw directoryName in authorityKeyId */ unsigned akid_raw_issuer_size; }; /* * Free an X.509 certificate */ void x509_free_certificate(struct x509_certificate *cert) { if (cert) { public_key_free(cert->pub); public_key_signature_free(cert->sig); kfree(cert->issuer); kfree(cert->subject); kfree(cert->id); kfree(cert->skid); kfree(cert); } } EXPORT_SYMBOL_GPL(x509_free_certificate); /* * Parse an X.509 certificate */ struct x509_certificate *x509_cert_parse(const void *data, size_t datalen) { struct x509_certificate *cert; struct x509_parse_context *ctx; struct asymmetric_key_id *kid; long ret; ret = -ENOMEM; cert = kzalloc(sizeof(struct x509_certificate), GFP_KERNEL); if (!cert) goto error_no_cert; cert->pub = kzalloc(sizeof(struct public_key), GFP_KERNEL); if (!cert->pub) goto error_no_ctx; cert->sig = kzalloc(sizeof(struct public_key_signature), GFP_KERNEL); if (!cert->sig) goto error_no_ctx; ctx = kzalloc(sizeof(struct x509_parse_context), GFP_KERNEL); if (!ctx) goto error_no_ctx; ctx->cert = cert; ctx->data = (unsigned long)data; /* Attempt to decode the certificate */ ret = asn1_ber_decoder(&x509_decoder, ctx, data, datalen); if (ret < 0) goto error_decode; /* Decode the AuthorityKeyIdentifier */ if (ctx->raw_akid) { pr_devel("AKID: %u %*phN\n", ctx->raw_akid_size, ctx->raw_akid_size, ctx->raw_akid); ret = asn1_ber_decoder(&x509_akid_decoder, ctx, ctx->raw_akid, ctx->raw_akid_size); if (ret < 0) { pr_warn("Couldn't decode AuthKeyIdentifier\n"); goto error_decode; } } ret = -ENOMEM; cert->pub->key = kmemdup(ctx->key, ctx->key_size, GFP_KERNEL); if (!cert->pub->key) goto error_decode; cert->pub->keylen = ctx->key_size; cert->pub->params = kmemdup(ctx->params, ctx->params_size, GFP_KERNEL); if (!cert->pub->params) goto error_decode; cert->pub->paramlen = ctx->params_size; cert->pub->algo = ctx->key_algo; /* Grab the signature bits */ ret = x509_get_sig_params(cert); if (ret < 0) goto error_decode; /* Generate cert issuer + serial number key ID */ kid = asymmetric_key_generate_id(cert->raw_serial, cert->raw_serial_size, cert->raw_issuer, cert->raw_issuer_size); if (IS_ERR(kid)) { ret = PTR_ERR(kid); goto error_decode; } cert->id = kid; /* Detect self-signed certificates */ ret = x509_check_for_self_signed(cert); if (ret < 0) goto error_decode; kfree(ctx); return cert; error_decode: kfree(ctx); error_no_ctx: x509_free_certificate(cert); error_no_cert: return ERR_PTR(ret); } EXPORT_SYMBOL_GPL(x509_cert_parse); /* * Note an OID when we find one for later processing when we know how * to interpret it. */ int x509_note_OID(void *context, size_t hdrlen, unsigned char tag, const void *value, size_t vlen) { struct x509_parse_context *ctx = context; ctx->last_oid = look_up_OID(value, vlen); if (ctx->last_oid == OID__NR) { char buffer[50]; sprint_oid(value, vlen, buffer, sizeof(buffer)); pr_debug("Unknown OID: [%lu] %s\n", (unsigned long)value - ctx->data, buffer); } return 0; } /* * Save the position of the TBS data so that we can check the signature over it * later. */ int x509_note_tbs_certificate(void *context, size_t hdrlen, unsigned char tag, const void *value, size_t vlen) { struct x509_parse_context *ctx = context; pr_debug("x509_note_tbs_certificate(,%zu,%02x,%ld,%zu)!\n", hdrlen, tag, (unsigned long)value - ctx->data, vlen); ctx->cert->tbs = value - hdrlen; ctx->cert->tbs_size = vlen + hdrlen; return 0; } /* * Record the algorithm that was used to sign this certificate. */ int x509_note_sig_algo(void *context, size_t hdrlen, unsigned char tag, const void *value, size_t vlen) { struct x509_parse_context *ctx = context; pr_debug("PubKey Algo: %u\n", ctx->last_oid); switch (ctx->last_oid) { case OID_md2WithRSAEncryption: case OID_md3WithRSAEncryption: default: return -ENOPKG; /* Unsupported combination */ case OID_md4WithRSAEncryption: ctx->cert->sig->hash_algo = "md4"; goto rsa_pkcs1; case OID_sha1WithRSAEncryption: ctx->cert->sig->hash_algo = "sha1"; goto rsa_pkcs1; case OID_sha256WithRSAEncryption: ctx->cert->sig->hash_algo = "sha256"; goto rsa_pkcs1; case OID_sha384WithRSAEncryption: ctx->cert->sig->hash_algo = "sha384"; goto rsa_pkcs1; case OID_sha512WithRSAEncryption: ctx->cert->sig->hash_algo = "sha512"; goto rsa_pkcs1; case OID_sha224WithRSAEncryption: ctx->cert->sig->hash_algo = "sha224"; goto rsa_pkcs1; case OID_id_ecdsa_with_sha1: ctx->cert->sig->hash_algo = "sha1"; goto ecdsa; case OID_id_ecdsa_with_sha224: ctx->cert->sig->hash_algo = "sha224"; goto ecdsa; case OID_id_ecdsa_with_sha256: ctx->cert->sig->hash_algo = "sha256"; goto ecdsa; case OID_id_ecdsa_with_sha384: ctx->cert->sig->hash_algo = "sha384"; goto ecdsa; case OID_id_ecdsa_with_sha512: ctx->cert->sig->hash_algo = "sha512"; goto ecdsa; case OID_gost2012Signature256: ctx->cert->sig->hash_algo = "streebog256"; goto ecrdsa; case OID_gost2012Signature512: ctx->cert->sig->hash_algo = "streebog512"; goto ecrdsa; case OID_SM2_with_SM3: ctx->cert->sig->hash_algo = "sm3"; goto sm2; } rsa_pkcs1: ctx->cert->sig->pkey_algo = "rsa"; ctx->cert->sig->encoding = "pkcs1"; ctx->sig_algo = ctx->last_oid; return 0; ecrdsa: ctx->cert->sig->pkey_algo = "ecrdsa"; ctx->cert->sig->encoding = "raw"; ctx->sig_algo = ctx->last_oid; return 0; sm2: ctx->cert->sig->pkey_algo = "sm2"; ctx->cert->sig->encoding = "raw"; ctx->sig_algo = ctx->last_oid; return 0; ecdsa: ctx->cert->sig->pkey_algo = "ecdsa"; ctx->cert->sig->encoding = "x962"; ctx->sig_algo = ctx->last_oid; return 0; } /* * Note the whereabouts and type of the signature. */ int x509_note_signature(void *context, size_t hdrlen, unsigned char tag, const void *value, size_t vlen) { struct x509_parse_context *ctx = context; pr_debug("Signature: alg=%u, size=%zu\n", ctx->last_oid, vlen); /* * In X.509 certificates, the signature's algorithm is stored in two * places: inside the TBSCertificate (the data that is signed), and * alongside the signature. These *must* match. */ if (ctx->last_oid != ctx->sig_algo) { pr_warn("signatureAlgorithm (%u) differs from tbsCertificate.signature (%u)\n", ctx->last_oid, ctx->sig_algo); return -EINVAL; } if (strcmp(ctx->cert->sig->pkey_algo, "rsa") == 0 || strcmp(ctx->cert->sig->pkey_algo, "ecrdsa") == 0 || strcmp(ctx->cert->sig->pkey_algo, "sm2") == 0 || strcmp(ctx->cert->sig->pkey_algo, "ecdsa") == 0) { /* Discard the BIT STRING metadata */ if (vlen < 1 || *(const u8 *)value != 0) return -EBADMSG; value++; vlen--; } ctx->cert->raw_sig = value; ctx->cert->raw_sig_size = vlen; return 0; } /* * Note the certificate serial number */ int x509_note_serial(void *context, size_t hdrlen, unsigned char tag, const void *value, size_t vlen) { struct x509_parse_context *ctx = context; ctx->cert->raw_serial = value; ctx->cert->raw_serial_size = vlen; return 0; } /* * Note some of the name segments from which we'll fabricate a name. */ int x509_extract_name_segment(void *context, size_t hdrlen, unsigned char tag, const void *value, size_t vlen) { struct x509_parse_context *ctx = context; switch (ctx->last_oid) { case OID_commonName: ctx->cn_size = vlen; ctx->cn_offset = (unsigned long)value - ctx->data; break; case OID_organizationName: ctx->o_size = vlen; ctx->o_offset = (unsigned long)value - ctx->data; break; case OID_email_address: ctx->email_size = vlen; ctx->email_offset = (unsigned long)value - ctx->data; break; default: break; } return 0; } /* * Fabricate and save the issuer and subject names */ static int x509_fabricate_name(struct x509_parse_context *ctx, size_t hdrlen, unsigned char tag, char **_name, size_t vlen) { const void *name, *data = (const void *)ctx->data; size_t namesize; char *buffer; if (*_name) return -EINVAL; /* Empty name string if no material */ if (!ctx->cn_size && !ctx->o_size && !ctx->email_size) { buffer = kmalloc(1, GFP_KERNEL); if (!buffer) return -ENOMEM; buffer[0] = 0; goto done; } if (ctx->cn_size && ctx->o_size) { /* Consider combining O and CN, but use only the CN if it is * prefixed by the O, or a significant portion thereof. */ namesize = ctx->cn_size; name = data + ctx->cn_offset; if (ctx->cn_size >= ctx->o_size && memcmp(data + ctx->cn_offset, data + ctx->o_offset, ctx->o_size) == 0) goto single_component; if (ctx->cn_size >= 7 && ctx->o_size >= 7 && memcmp(data + ctx->cn_offset, data + ctx->o_offset, 7) == 0) goto single_component; buffer = kmalloc(ctx->o_size + 2 + ctx->cn_size + 1, GFP_KERNEL); if (!buffer) return -ENOMEM; memcpy(buffer, data + ctx->o_offset, ctx->o_size); buffer[ctx->o_size + 0] = ':'; buffer[ctx->o_size + 1] = ' '; memcpy(buffer + ctx->o_size + 2, data + ctx->cn_offset, ctx->cn_size); buffer[ctx->o_size + 2 + ctx->cn_size] = 0; goto done; } else if (ctx->cn_size) { namesize = ctx->cn_size; name = data + ctx->cn_offset; } else if (ctx->o_size) { namesize = ctx->o_size; name = data + ctx->o_offset; } else { namesize = ctx->email_size; name = data + ctx->email_offset; } single_component: buffer = kmalloc(namesize + 1, GFP_KERNEL); if (!buffer) return -ENOMEM; memcpy(buffer, name, namesize); buffer[namesize] = 0; done: *_name = buffer; ctx->cn_size = 0; ctx->o_size = 0; ctx->email_size = 0; return 0; } int x509_note_issuer(void *context, size_t hdrlen, unsigned char tag, const void *value, size_t vlen) { struct x509_parse_context *ctx = context; struct asymmetric_key_id *kid; ctx->cert->raw_issuer = value; ctx->cert->raw_issuer_size = vlen; if (!ctx->cert->sig->auth_ids[2]) { kid = asymmetric_key_generate_id(value, vlen, "", 0); if (IS_ERR(kid)) return PTR_ERR(kid); ctx->cert->sig->auth_ids[2] = kid; } return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->issuer, vlen); } int x509_note_subject(void *context, size_t hdrlen, unsigned char tag, const void *value, size_t vlen) { struct x509_parse_context *ctx = context; ctx->cert->raw_subject = value; ctx->cert->raw_subject_size = vlen; return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->subject, vlen); } /* * Extract the parameters for the public key */ int x509_note_params(void *context, size_t hdrlen, unsigned char tag, const void *value, size_t vlen) { struct x509_parse_context *ctx = context; /* * AlgorithmIdentifier is used three times in the x509, we should skip * first and ignore third, using second one which is after subject and * before subjectPublicKey. */ if (!ctx->cert->raw_subject || ctx->key) return 0; ctx->params = value - hdrlen; ctx->params_size = vlen + hdrlen; return 0; } /* * Extract the data for the public key algorithm */ int x509_extract_key_data(void *context, size_t hdrlen, unsigned char tag, const void *value, size_t vlen) { struct x509_parse_context *ctx = context; enum OID oid; ctx->key_algo = ctx->last_oid; switch (ctx->last_oid) { case OID_rsaEncryption: ctx->cert->pub->pkey_algo = "rsa"; break; case OID_gost2012PKey256: case OID_gost2012PKey512: ctx->cert->pub->pkey_algo = "ecrdsa"; break; case OID_sm2: ctx->cert->pub->pkey_algo = "sm2"; break; case OID_id_ecPublicKey: if (parse_OID(ctx->params, ctx->params_size, &oid) != 0) return -EBADMSG; switch (oid) { case OID_sm2: ctx->cert->pub->pkey_algo = "sm2"; break; case OID_id_prime192v1: ctx->cert->pub->pkey_algo = "ecdsa-nist-p192"; break; case OID_id_prime256v1: ctx->cert->pub->pkey_algo = "ecdsa-nist-p256"; break; case OID_id_ansip384r1: ctx->cert->pub->pkey_algo = "ecdsa-nist-p384"; break; default: return -ENOPKG; } break; default: return -ENOPKG; } /* Discard the BIT STRING metadata */ if (vlen < 1 || *(const u8 *)value != 0) return -EBADMSG; ctx->key = value + 1; ctx->key_size = vlen - 1; return 0; } /* The keyIdentifier in AuthorityKeyIdentifier SEQUENCE is tag(CONT,PRIM,0) */ #define SEQ_TAG_KEYID (ASN1_CONT << 6) /* * Process certificate extensions that are used to qualify the certificate. */ int x509_process_extension(void *context, size_t hdrlen, unsigned char tag, const void *value, size_t vlen) { struct x509_parse_context *ctx = context; struct asymmetric_key_id *kid; const unsigned char *v = value; pr_debug("Extension: %u\n", ctx->last_oid); if (ctx->last_oid == OID_subjectKeyIdentifier) { /* Get hold of the key fingerprint */ if (ctx->cert->skid || vlen < 3) return -EBADMSG; if (v[0] != ASN1_OTS || v[1] != vlen - 2) return -EBADMSG; v += 2; vlen -= 2; ctx->cert->raw_skid_size = vlen; ctx->cert->raw_skid = v; kid = asymmetric_key_generate_id(v, vlen, "", 0); if (IS_ERR(kid)) return PTR_ERR(kid); ctx->cert->skid = kid; pr_debug("subjkeyid %*phN\n", kid->len, kid->data); return 0; } if (ctx->last_oid == OID_keyUsage) { /* * Get hold of the keyUsage bit string * v[1] is the encoding size * (Expect either 0x02 or 0x03, making it 1 or 2 bytes) * v[2] is the number of unused bits in the bit string * (If >= 3 keyCertSign is missing when v[1] = 0x02) * v[3] and possibly v[4] contain the bit string * * From RFC 5280 4.2.1.3: * 0x04 is where keyCertSign lands in this bit string * 0x80 is where digitalSignature lands in this bit string */ if (v[0] != ASN1_BTS) return -EBADMSG; if (vlen < 4) return -EBADMSG; if (v[2] >= 8) return -EBADMSG; if (v[3] & 0x80) ctx->cert->pub->key_eflags |= 1 << KEY_EFLAG_DIGITALSIG; if (v[1] == 0x02 && v[2] <= 2 && (v[3] & 0x04)) ctx->cert->pub->key_eflags |= 1 << KEY_EFLAG_KEYCERTSIGN; else if (vlen > 4 && v[1] == 0x03 && (v[3] & 0x04)) ctx->cert->pub->key_eflags |= 1 << KEY_EFLAG_KEYCERTSIGN; return 0; } if (ctx->last_oid == OID_authorityKeyIdentifier) { /* Get hold of the CA key fingerprint */ ctx->raw_akid = v; ctx->raw_akid_size = vlen; return 0; } if (ctx->last_oid == OID_basicConstraints) { /* * Get hold of the basicConstraints * v[1] is the encoding size * (Expect 0x2 or greater, making it 1 or more bytes) * v[2] is the encoding type * (Expect an ASN1_BOOL for the CA) * v[3] is the contents of the ASN1_BOOL * (Expect 1 if the CA is TRUE) * vlen should match the entire extension size */ if (v[0] != (ASN1_CONS_BIT | ASN1_SEQ)) return -EBADMSG; if (vlen < 2) return -EBADMSG; if (v[1] != vlen - 2) return -EBADMSG; if (vlen >= 4 && v[1] != 0 && v[2] == ASN1_BOOL && v[3] == 1) ctx->cert->pub->key_eflags |= 1 << KEY_EFLAG_CA; return 0; } return 0; } /** * x509_decode_time - Decode an X.509 time ASN.1 object * @_t: The time to fill in * @hdrlen: The length of the object header * @tag: The object tag * @value: The object value * @vlen: The size of the object value * * Decode an ASN.1 universal time or generalised time field into a struct the * kernel can handle and check it for validity. The time is decoded thus: * * [RFC5280 ยง4.1.2.5] * CAs conforming to this profile MUST always encode certificate validity * dates through the year 2049 as UTCTime; certificate validity dates in * 2050 or later MUST be encoded as GeneralizedTime. Conforming * applications MUST be able to process validity dates that are encoded in * either UTCTime or GeneralizedTime. */ int x509_decode_time(time64_t *_t, size_t hdrlen, unsigned char tag, const unsigned char *value, size_t vlen) { static const unsigned char month_lengths[] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }; const unsigned char *p = value; unsigned year, mon, day, hour, min, sec, mon_len; #define dec2bin(X) ({ unsigned char x = (X) - '0'; if (x > 9) goto invalid_time; x; }) #define DD2bin(P) ({ unsigned x = dec2bin(P[0]) * 10 + dec2bin(P[1]); P += 2; x; }) if (tag == ASN1_UNITIM) { /* UTCTime: YYMMDDHHMMSSZ */ if (vlen != 13) goto unsupported_time; year = DD2bin(p); if (year >= 50) year += 1900; else year += 2000; } else if (tag == ASN1_GENTIM) { /* GenTime: YYYYMMDDHHMMSSZ */ if (vlen != 15) goto unsupported_time; year = DD2bin(p) * 100 + DD2bin(p); if (year >= 1950 && year <= 2049) goto invalid_time; } else { goto unsupported_time; } mon = DD2bin(p); day = DD2bin(p); hour = DD2bin(p); min = DD2bin(p); sec = DD2bin(p); if (*p != 'Z') goto unsupported_time; if (year < 1970 || mon < 1 || mon > 12) goto invalid_time; mon_len = month_lengths[mon - 1]; if (mon == 2) { if (year % 4 == 0) { mon_len = 29; if (year % 100 == 0) { mon_len = 28; if (year % 400 == 0) mon_len = 29; } } } if (day < 1 || day > mon_len || hour > 24 || /* ISO 8601 permits 24:00:00 as midnight tomorrow */ min > 59 || sec > 60) /* ISO 8601 permits leap seconds [X.680 46.3] */ goto invalid_time; *_t = mktime64(year, mon, day, hour, min, sec); return 0; unsupported_time: pr_debug("Got unsupported time [tag %02x]: '%*phN'\n", tag, (int)vlen, value); return -EBADMSG; invalid_time: pr_debug("Got invalid time [tag %02x]: '%*phN'\n", tag, (int)vlen, value); return -EBADMSG; } EXPORT_SYMBOL_GPL(x509_decode_time); int x509_note_not_before(void *context, size_t hdrlen, unsigned char tag, const void *value, size_t vlen) { struct x509_parse_context *ctx = context; return x509_decode_time(&ctx->cert->valid_from, hdrlen, tag, value, vlen); } int x509_note_not_after(void *context, size_t hdrlen, unsigned char tag, const void *value, size_t vlen) { struct x509_parse_context *ctx = context; return x509_decode_time(&ctx->cert->valid_to, hdrlen, tag, value, vlen); } /* * Note a key identifier-based AuthorityKeyIdentifier */ int x509_akid_note_kid(void *context, size_t hdrlen, unsigned char tag, const void *value, size_t vlen) { struct x509_parse_context *ctx = context; struct asymmetric_key_id *kid; pr_debug("AKID: keyid: %*phN\n", (int)vlen, value); if (ctx->cert->sig->auth_ids[1]) return 0; kid = asymmetric_key_generate_id(value, vlen, "", 0); if (IS_ERR(kid)) return PTR_ERR(kid); pr_debug("authkeyid %*phN\n", kid->len, kid->data); ctx->cert->sig->auth_ids[1] = kid; return 0; } /* * Note a directoryName in an AuthorityKeyIdentifier */ int x509_akid_note_name(void *context, size_t hdrlen, unsigned char tag, const void *value, size_t vlen) { struct x509_parse_context *ctx = context; pr_debug("AKID: name: %*phN\n", (int)vlen, value); ctx->akid_raw_issuer = value; ctx->akid_raw_issuer_size = vlen; return 0; } /* * Note a serial number in an AuthorityKeyIdentifier */ int x509_akid_note_serial(void *context, size_t hdrlen, unsigned char tag, const void *value, size_t vlen) { struct x509_parse_context *ctx = context; struct asymmetric_key_id *kid; pr_debug("AKID: serial: %*phN\n", (int)vlen, value); if (!ctx->akid_raw_issuer || ctx->cert->sig->auth_ids[0]) return 0; kid = asymmetric_key_generate_id(value, vlen, ctx->akid_raw_issuer, ctx->akid_raw_issuer_size); if (IS_ERR(kid)) return PTR_ERR(kid); pr_debug("authkeyid %*phN\n", kid->len, kid->data); ctx->cert->sig->auth_ids[0] = kid; return 0; }